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'drinking water. . 

Source protection 



ACT FOR CLEAN WATER 



Technical Bulletin: Delineation of Intake Protection Zone 3 



Using the Event Based Approach (EBA) 

Date: July 2009 



1- Introduction 

The Clean Water Act requires the Source Protection Committee to prepare an 
Assessment Report for each source protection area they represent, in accordance with 
the regulations, the Director's Technical Rules and the approved terms of reference for 
that source protection area. 

As part of the Assessment Report, committees must identify four types of vulnerable 
areas within each Source Protection Area. These include wellhead protection areas 
(WHPAs), intake protection zones (IPZs), highly vulnerable aquifers (HVAs), and 
significant groundwater recharge areas (SGRAs). Once these areas are delineated, the 
rules require that vulnerability scores be assigned within these areas. 

This technical bulletin provides guidance to Source Protection Committees on the 
process of identifying and delineating Intake Protection Zone 3 (IPZ-3) using the Event 
Based Approach (EBA) under the Technical Rules for the Assessment Report - Part VI.5 
rules 68 and 69. The event based approach can be used for Type A and B intakes located 
at Great Lakes and Connecting Channels, and for Type C and D intakes located on Lake 
Nipissing, Lake Simcoe, Lake St. Clair and the Ottawa River. Requirements for assigning 
vulnerability scores to the IPZs are set out in Part VIII of the Technical Rules and are not 
addressed in this bulletin. 

The Technical Rules allow the Source Protection Committees to use a number of 
methods to identify and delineate the IPZ-3 as set out below. This Technical Bulletin 




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en exempte I'appkation de la Loi sur les services en frangais. Pour obtenir de I'aide en frangais, veuiilez 
communiquer avec le ministere de I'Environnementau 416-212-5296, ou sourceprotection@ Ontario. ca 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
references that Director's Technical Rules published by the Ministry of the Environment 
on December 12, 2008. 

Part VI.5 of the Technical Rules states, 

68. An area known as IPZ-3 shall be delineated for each type A and type B 
surface water intake and each type C and type D surface water intake located 
in Lake Nippissing, Lake Simcoe, Lake St. Clair or the Ottawa River, 
associated with a drinking water system described in rule 58 and shall be 
composed of the following areas: Subject to rule 69, the area within each 
surface water body through which, modeling demonstrates, contaminants 
released during an extreme event may be transported to the intake; 

(1) where the area delineated in accordance with subrule (1) abuts land, 

(a) a setback of not more than 120 metres inland along the abutted land measured 
from the high water mark of the surface water body that encompasses the area 
where overland flow drains into the surface water body; and 

(b) the area of the Regulation Limit along the abutted land. 

69. The area delineated in accordance with subrule 6868 shall not exceed the area within each 
surface water body that may contribute water to the intake during or as a result of an 
extreme event. 

The first step in the EBA is to delineate an IPZ-3 that includes areas beyond IPZ-1 and 
IPZ-2, based on extreme event conditions and an understanding of contaminant 
transport to the intake. The EBA then allows activities to be identified as a significant 
drinking water threat if it can be shown through modeling that a release of a specific 
contaminant from an activity would result in an issue at the intake. The identification of 
such an activity is governed under rule 130 of the Technical Rules, as follows: 

130. An activity listed as a drinking water threat in accordance with rule 118 or 119 is a 

significant drinking water threat in an IPZ-3 delineated in accordance with rule 68 at the 
location where the activity is carried on if modeling demonstrates that a release of a 
chemical parameter or pathogen from the activity would be transported through the surface 
water intake protection zone to the intake and result in the deterioration of the water for use 
as a source of drinking water for the intake. 

2- IPZ-3 Delineation Options 

Figure 1 shows a flowchart with three options to delineate IPZ-3 using the EBA. The SPC 
may decide which option is appropriate for the drinking water system in question based 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
on the data and information available on the water bodies and any activity(ies) they 
might be concerned about. The three options are discussed in more detail in sections 2.1 
to 2.3. 

Two relevant criteria in delineating IPZ-3 (EBA) for all three options are the flood event 
discharge and time of travel. 

The flood event discharge can be estimated by considering an extreme wind storm event 
or 100 year flood event or snowmelt event during spring times (freshet) or any 
combination that in the opinion of the SPC represents the 100 year combined probability 
of an extreme event. The Technical Rules also allow less frequent storm events to be 
considered. 

Time of travel (ToT) is a key issue in determining the IPZ-3 boundary. Based on the 
understanding of the flood event hydrograph (flood wave duration) and the stream- 
river system responses to flood events, a time of travel can be estimated with one of the 
following alternatives: 



IPZ-3 Delineation 



4- 



Conditions: 100 yr wind storm event, 100 yr flood event, or freshet or any 
combination that in the opinion of the SPC represents the 100 year combined 
probability of an extreme event. The Technical Rules also allow less frequent storm 
events to be considered. 



1 


' 




i 


r 




i 


r 


Option (1): 




Option (2): 




Option (3): 


i 


' 




i 


' 




i 


' 


Delineate IPZ-3 using the estimated distance or area given by any of the above three 
options and adding any transport pathways, setbacks or the regulation limit as 
required by the Technical Rules. 



Fig. 1: Flowchart on options used for delineating IPZ-3. 



Watershed 



Discharge 

▲ 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

Alternative 1: Unit Hydrograph 

This method can be 

applied if the unit 

hydrographs are known 

at particular gauging 

stations. In figure 2, 

assume there are two 

gauging stations GS1 and 

GS2 where the unit flood 

hydrograph is measured 

or calculated at those 

stations. The time 

difference between the 

flood peaks, T, may 

represent the time of 

travel for the distance 

between the two gauging stations. The time of travel (ToT) from an activity that is being 

modeled to the intake can be interpolated or extrapolated depending on its distance to 

either of the gauging stations. For example, assume an activity is located at a certain 

distance between GS1 and GS2; the time of travel for that activity can be obtained by 

interpolating the time of travel between the two stations and the distance between the 

activity and the two stations. 





Time 



Fig. 2: Illustration of unit hydrographs related to 
time of travel (ToT). 



The same concept can be applied if an activity is located 
outside the distance between GS1 and GS2 but in this case 
the ToT is obtained by extrapolation. The unit hydrograph 
method assumes that the flow is uniform and under 
steady state conditions along the entire stream/river reach, 
which is not always the case. The estimated time of travel 
depends on the accuracy of the data and an 
understanding of the input, output and storage volumes 
of water within that stream / river system. 

Alternative 2: Time of Concentration 

If the unit hydrographs mentioned in method (1) are not 
available, the time of concentration equation based the 
Soil Conservation Service (SCS) lag formula can be used, 
equation 1. The time of concentration, tc, is defined as the 
amount of time for the entire watershed to contribute to 
the outflow or the amount of time for the water to reach 



Watershed 




Fig. 3: Illustration of a 
watershed with the 
longest hydraulic path. 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
the outlet from the furthest point from the outlet. The tc formula is a function of the 
watershed length, L, the watershed slope, Sw, and the curve number, CN. The length L 
can be estimated from the data set related to the watershed and it is the longest 
hydraulic path in the watershed. The slop, Sw, is the average slope of the watershed 
which equals to elevation difference between point A and point B over the watershed 
length, L, see figure 3. 



t =0.00526L° 



1000 



CN 



? Eq.l 



Where tc is the time of concentration (min), which is equivalent to the time of travel, L is 
the watershed length (ft), Sw is the average watershed slope (ft/ft) and CN is the curve 
number (-). 

The curve number, CN, is the parameter that represents the potential maximum 
retention of rainfall. The Curve Number depends on the soil type (Group A, B, C, or D), 
land use and moisture conditions. Examples of suggested Curve Numbers for use with 
SCS hydrology is given in Table 1. However, users can calculate an appropriate value 
for CN based on the watershed characterisation. For additional information, see Urban 
Hydrology for Small Watersheds, Technical Release 55, United States Department of 
Agriculture, June 1986 and McCuen, 1998. 



Technical Bulletin: Delineation of Intake Protection Zone 3 








Using the Event Based 


Approach (EBA) 










Table 1: Curve Numbers for different types of Hydrologic Soil Group (McCuen, 1998). 








Hydrologic 


Soil Group 


Land Use Description 




A 


B 


C 


D 


Fully developed urban areas* {vegetation established) 












Lawns, open spaces, parks, golf courses, cemeteries, etc. 












Good condition; grass cover on 75% or more of the area 




39 


61 


74 


80 


Fair condition; grass cover on 50% to 75% of the area 




49 


69 


79 


84 


Poor condition; grass cover on 50% or less of the area 




68 


79 


86 


89 


Paved parking lots, roofs, driveways, etc. 




98 


98 


98 


98 


Streets and roads 












Paved with curbs and storm sewers 




98 


98 


98 


98 


Gravel 




76 


85 


89 


91 


Dirt 




72 


82 


87 


89 


Paved with open ditches 


Average % impervious* 1 


83 


89 


92 


93 


Commercial and business areas 


85 


89 


92 


94 


95 


Industrial districts 


72 


81 


88 


91 


93 


Row houses, town houses, and residential with lots sizes 


65 


77 


85 


90 


92 


1/8 acre or less 












Residential; average lot size 












1/4 acre 


38 


6) 


75 


83 


87 


1/3 acre 


30 


57 


72 


81 


86 


1/2 acre 


25 


54 


70 


80 


85 


1 acre 


20 


51 


68 


79 


84 


2 acre 


12 


46 


65 


77 


82 


Developing urban areas c (no vegetation established) 












Newly graded area 




77 


86 


91 


94 


Western desert urban areas 












Natural desert landscaping (pervious area only/ 




63 


77 


85 


88 


Artificial desert landscaping 




96 


96 


96 


96 






Curve Numbers for 






Hydrologic 


Soil Group 




Hydrologic 










Land Use Description Treatment or Practice 15 


Condition 


A 


B 


C 


D 


Cultivated agricultural land 












Fallow Straight row or bare soil 




77 


86 


91 


94 


Conservation tillage 


Poor 


76 


85 


90 


93 


Conservation tillage 


Good 


74 


S3 


88 


90 


Row crops Straight row 


Poor 


72 


81 


88 


91 


Straight row 


Good 


67 


78 


85 


89 


Conservation tillage 


Poor 


71 


80 


87 


90 


Conservation tillage 


Good 


64 


75 


82 


85 


Contoured 


Poor 


70 


79 


84 


88 


Contoured 


Good 


65 


75 


82 


86 


Contoured and 


Poor 


69 


78 


83 


87 


conservation tillage 


Good 


64 


74 


81 


85 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
The time of concentration formula is an empirical formula that is based on a number of 
assumptions and therefore, will, in most cases, produce a smaller IPZ-3 than if more 
advanced modelling was available. However, this method is a good starting method to 
estimate the time of travel within the watershed in the absence of an advanced 
numerical model. The formula is intended for use on watersheds where overland flow 
dominates and was developed for non-urban watersheds of 4000 acres or less. This does 
not mean it can not be used to determine a time of travel in a more urban watershed, but 
does mean that the numbers may be lower than expected in these types of watershed. 
Time of travel calculated using this formula is based on the following assumptions: 
average slope of the watershed, one type of land use and soil and an approximated 
watershed length. 

If neither the alternative (1) nor the alternative (2) can be used, the time of travel (ToT) 
for a watershed can be the same time of travel of another watershed if both watersheds 
have similar characterisations. 

2.1 Option 1: Contaminant Transport Approach: 

If the SPC is concerned about specific activities that are being carried out upstream of 
the surface water intake, this approach can be used to determine the transport of 
contaminant(s) to the intake. If the contaminant reaches the intake, the IPZ-3 boundary 
can be delineated including the area of that activity. With this approach, the SPC would 
need to determine a concentration threshold to decide whether a contaminant released 
at the location of the activity in question has reached the intake or not. If not, i.e. the SPC 
decides the concentration of the contaminant is too low for it to be considered reaching 
the intake, then the location of that activity may not be included in the delineation of an 
IPZ-3. An understanding of contaminant transport from a number of activities can then 
be used to determine the extent of the IPZ-3. 

As a second step, if the contaminant reaches the intake and results in the deterioration of 
the water quality (as per Rule 130), then this activity would be identified as a significant 
drinking water threat. The IPZ-3 delineation will include the contributing area of the 
activity(ies) that cause(s) an issue at the surface water intake. 

Methods that can be used to delineate IPZ-3: 

a- Numerical models (ID, 2D or 3D) 

b- Analytical approach (explained below in section 3.4). This approach does not need a 
time of travel to be determined. 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
Required inputs to apply option (1): flood discharge, estimated time of travel, and mass 
of the contaminant, either continuous or instant. The estimated TOT may be used as the 
simulation time if a numerical model is used. 

2.2 Option 2: Boundary Approach: 

This option can be used if in the opinion of the SPC there are no activities of concern 
upstream of the intake. This approach determines the boundary of IPZ-3 within the 
water body without analysing specific activity(ies). This approach requires that a time of 
travel (ToT) is determined as mentioned above. The assumption would be that whatever 
is released within the chosen ToT would reach the intake (under specific storm event 
conditions). 

Methods that can be used to delineate IPZ-3: 

a- Particle Tracking 

b- Numerical Model (ID) 

c- Manning equation 

Required inputs to apply the option (2): flood discharge and estimated time of travel, 
which may be used as the simulation time if a numerical model is used. 

2.3 Option 3: Combined Approach: 

This approach is a combination of option (1) and (2). As a first step, option (2) is used to 
delineate the IPZ-3. As a second step, if the SPC is concerned about specific activities 
that are located inside or outside the IPZ-3, option (1) would then be used to determine 
whether the IPZ-3 needs to be expanded or reduced, by determining whether the 
contaminant from a specific activity reaches the intake or not. As in option 1, the SPC 
would need to determine a concentration threshold to decide whether a contaminant has 
reached the intake or not. If yes, modify the delineated IPZ-3 to include (or exclude) the 
contributing area of that activity. As a third step, the SPC can then determine whether 
the activity causes an issue or not (as per Rule 130). 

Methods that can be used to delineate IPZ-3 in option (3) are a combination of methods 
mentioned in option (1) and option (2). 

3- Supporting Methods 

There are several physical processes controlling the transport of contaminants in river 
systems: mixing; molecular diffusion; turbulent diffusion; dispersion; advection; 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
dilution (decay function); and sorption. The mixing process is affected by the spatial 
variation of velocity on the macroscopic scale according to the Fick's law 1855. 

If an activity discharges into a stream, the initial mixing of a contaminant is determined 
by the momentum and buoyancy forces of the discharge. As the contaminant is diluted, 
those forces disappear and the transport of the contaminant is dominated by ambient 
water velocity variation in the stream. Then, the contaminant plume is spread along the 
stream by dispersion and advection . Typical flow velocities of rivers range from 0.1 m/s 
to 1.5 m/s corresponding to channel slopes of 0.02% to 1% (Chin, 2006). 

Numerical models are one of the tools that can be used to delineate the IPZ-3. Simple 
analytical approaches or particle tracking are other options to estimate the concentration 
of contaminants in the water bodies. Particle tracking is one of the more recently 
developed tools that provide information on the distance from an intake that particles 
can be transported through by knowing the flow velocities and concentration of the 
particles. This document presents an overview of the numerical models but focuses 
more on an analytical approach that can help users to calculate the distance 
contaminants are transported in a water system. 

3.1 Numerical Codes 

Several numerical codes are now available to simulate water quality in rivers and 
streams. Most codes typically provide numerical solutions to the advection-dispersion 
equation or some other forms of the law of mass conservation. The numerical solutions 
are produced at discrete locations and times for complex boundary conditions, and 
spatially and temporally disturbed contaminant transport. The numerical codes used in 
practical engineering are mostly ID and 2D. 3D numerical codes are sometimes used but 
generally more costly. Numerical codes are commonly used to facilitate the analysis of 
fate and transport process of contaminants in river systems and include QUAL2E, HSPS, 
WASP6, SED2D, MIKE family, DELFT family, TELEMAC system, and HEC-6. It is up to 
the user to select the appropriate numerical model to simulate the contaminant transport 
based on the capabilities and limitations of each model and the local condition. 

3.2 Particle Tracking Method 

Particle tracking is a technique that is linked to hydrodynamic numerical models. The 
particle tracking method describes the effects of molecular and turbulent diffusion on 
the dispersion of constituents with time and can determine path lines in spatially 
variable parameter domains. When calculations are computed in reverse time, it is called 
Reverse Particle Tracking (RPT) and when computed in forward time it is call Forward 
Particle Tracking (FRT). The particle tracking method identifies an area from points of 
withdrawal that are likely to contribute flow to the intake within a specific time period. 
To use the particle tracking method, the location of an intake should be determined in 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
both x and y directions if two-dimensional approach is used and in x, y and z directions 
if a three-dimensional approach is used. The number of hypothetical particles for 
tracking analyses should be specified as well as the time of travel (ToT) to determine the 
distance of the traveling particles. The diffusion rate of particles is controlled by flow 
velocities and longitudinal and transverse diffusions. This method determines the 
distance traveled in the water body, and as a second step the transport pathways, 
setbacks or regulation limit need to be added to delineate the IPZ-3. 

3.3 Manning Equation 

The Manning Equation is the most commonly used equation to analyze open channel 
flows. It is a semi-empirical equation for simulating water flows in channels and 
culverts where the water is open to the atmosphere, i.e. not flowing under pressure. The 
distance from the intake can be determined as follows: 

D = V.T ,V = -R 2/3 S 1 ' 2 (Part a) or V = — (Part b) Eq. 2 

n A 

Where D is the distance from an intake in the water body (m), T is the estimated time of 
travel as explained (s), n is the Manning coefficient (friction coefficient), which varies 
from 0.001 to 0.03 based on type of stream bed material and flow, R is the hydraulic 
radius (m) which in most cases is equivalent to the water depth of river, and S is the 
energy slope which is equivalent to the stream slope. 

If the inflow discharge of a flood event is known, then the flow velocity can be 
determined through equation 2, part b. If the water depth at the flood event is known 
but not the discharge, then equation 1, part a can be used to calculate the flow velocity. 
Then the distance, D, from the surface water intake can be determined. This approach 
determines the distance traveled in the water body, and as a second step the transport 
pathways, setbacks or regulation limit need to be added to delineate the IPZ-3. 

3.4 Analytical Approach 

The analytical approach provides a mechanism that can be used if the contaminant mass 
and type entering a water body are known. The analytical approach can be used for 
point source discharges such as industrial or municipal discharges, stormwater 
discharges, or spills, and considers the physical properties of the contaminants only. 
Spills in rivers or streams can be a result of major collisions on transportation routes or 
failures at large storage sites. Spills can be thought of as large masses of contaminants 
that are released in a very short period of time. 

Non-point sources of contaminants, such as runoff from rural or agricultural areas and 
urban runoff are not considered in this approach. The main goal is to determine the 



10 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
concentration of a contaminant at the surface water intake according to option (1). There 
are two concepts that can be used to calculate the concentration of a contaminant: 1) 
without dispersion and 2) with dispersion. 

3.4.1 No dispersion 

If full mixing, decay and no dispersion are considered, equation 4 calculates the 
concentration at a certain distance. To do that, first determine the mean concentration of 
a contaminant after mixing; see figure 4, with the water body of the stream through 
equation 3: 



QC+QC = Q. .C =>C = 



QC+QC 
Q, + Q ... 



Eq.3 



Fig.4: 

Initial mixing of 
waste discharge with 
stream discharge. 



MbcedTlischarge 




Waste Discharge 
O... C... 



For simplicity, it can be assumed that the discharge of a contaminant is well mixed 
across the cross section. 



C(x,t) = C o e Q Eq.4 

Where C is the concentration of the contaminant at the surface water intake (kg/m 3 ), X is 
the distance between the point discharge from an activity projected on the stream flow 
and the surface water intake along the stream line (m), *#■ is the decay (s 1 ), A is the wet 
cross sectional area of the stream (m 2 ) and Q is the discharge that has been determined 
to represent the extreme event (m 3 /s). 



11 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

The coefficient, "k, can be expressed in terms of the half-life, T50, which is the time 
required for 50% of the initial mass to decay as follows, equation 5: 

T lfl2 V R 

T 5 o = — Eq.5 

The half-life time depends on the type of chemical or contaminant released. An example 
of the half-life time of several organic compounds in soils has been compiled by Howard 
et ah, 1991, see Table 2. Users will need to determine the correct value for the 
contaminant(s) in question. 

Table 2: First order decay rates of selected organic compounds in Soil . 



Compound 



Half-Life, 7/ 50 < days) 



First-Order Decay Rate, A (day- 1 ) 



Acetone 


J— 14 


Benzene 


10-730 


Bi s(2-ethy lhexy 1 Jphthalate 


10-389 


Carbon tetrachloride 


7-365 


ChLoioetbane 


14-56 


Chloroform 


56-1800 


1,1-Dichloroethane 


64-154 


1, 2-Dichloroethane 


100-365 


Ethylbeitzeite 


6-228 


Methyl im-butyl ether 


56-365 


Methylene chloride 


14-56 


Naphthalene 


1-258 


Phenol 


0,5-7 


Toluene 


7-28 


1 , 1 , 1-Tric hloroe t hane 


140-546 


Trichloroethene 


321-1650 


Vinyl chloiide 


56-2880 


Xylenes 


14-365 



01050-0.35 

0.00095^.069 
0.00178-0.069 
0.001 9-OM9 
0,0124-0,0495 
0.000385-0,0124 
0.00450-0.0108 
0.00 190-0.00693 
0.00304^.116 
0.00190-0.0124 
0.0124^).O495 
O.O0269-0.693 
0.099-1.39 
O0248-0.099 
0.00127^3.00495 
0.000420-0.00216 
0.000241-0.0124 
0.00190-0.0495 



Sounre: Howard et al. (1991). 



12 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

3.4.2 With dispersion 

If full mixing, decay, longitudinal dispersion, mass of contaminant released are 
considered, the following can be applied: 

The governing equation for longitudinal dispersion that is well mixed over the cross 
sections of rivers and streams is given in equation 6. This equation considers dispersion 
and first order decay and assumes that a mass of contaminant, M, is instantaneously 
mixed over the cross section of the stream at time t=0. 



r*, « Me 

C(x,t) = — exp 

A^jiKJ 



(x - Vt) 2 
4K L t 



Eq.6 



Where C is the concentration of contaminant (kg/m 3 ) at a point, M is the mass of 
contaminant released from the facility (kg), V is the average flow velocity (m/s), Kl is the 
longitudinal dispersion (m 2 /s), "k is the coefficient that includes dilution (decay); 
dissolved oxygen concentration; water temperature etc. (s 1 ), and A is the cross-sectional 
area of the stream (m 2 ). If the contaminant is assumed to be conservative, then the decay 
coefficient is equal to zero. The exponential term in equation 6 is equal to 1 if the flow is 
uniform and steady. This term appears only when the water body is stagnant, i.e., V=0. 

In equation 6: the flow velocity can be calculated from the determined flow discharge 
that represents the extreme event discharge, Q, and average cross-sectional area of the 
stream, A. The time, t, can be calculated by knowing the average flow velocity, V, in the 
stream and the distance between the surface water intake and the projected location of 
the activity on the stream. The mass of contaminant should be specified based on 
available data of the activity. 

One of the first approaches to estimate the dispersion coefficient in river systems, Kl, is 
mentioned in Elder 1959 which states that K L = 5.93u,d where d is the mean depth of 
stream (m) and u* is the shear velocity of flow (m/s). However, several new approaches 
have been developed to estimate the Kl, and a summary of them is given in Table 3. To 
apply the equations shown in Table 3, the stream width must be larger than the mean 
water depth (w » d) where longitudinal dispersion is dominated by transverse 
variations in the mean velocity and the dispersion caused by vertical variations in mean 
velocity is relatively small. Typical values of Kl are 0.05m 2 /s to 0.3m 2 /s for small streams 
(Genereux, 1991) and as high as 1000m 2 /s for larger rivers (Wanner et al., 1989). 



13 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

Table 3: Estimates of the Longitudinal Dispersion Coefficient in Rivers, Chin 2006. 



Formula 



Reference 






d 

K. 






J. 

d 



d 



H* \ d j 

^=5.9i5feW-^r 



</«* 



</«* 



= 0.01875 



0,145 + - 



1 V /wW 



3520 it, U 



TV \W_V V 



Fischer el aid 979) 

Uu(1977) 

Koussis and Rodriguez-Mirasol 
U99S) 

Iwasa and Aya ( 199 1) 
Seo and Cheong (1998) 
Deng etal (2001) 



The shear flow velocity, u*, in Table 3 can be determined from equation 7, 



u = J "°/p ; ^o = pg R S; R = a/p Eq.7 

Where ~k* is the mean shear stress on the wetted perimeter (N/m 2 ), "k is the water density 
(kg/m 3 ), g is the gravity (m/s 2 ), R is the hydraulic radius (m), P is the wetted perimeter 
(m), A is the cross section (m 2 ) and S is the energy slope (-). To apply this equation the 
average water depth in the stream should be known. For simplicity, the energy slope can 
be assumed to be equal to the stream slope. The wetted perimeter, P, is the sum of all 
wet lengths along the cross section, see figure 5: 




1 




Fig. 5: Illustration of wetted perimeter over different cross sections of streams. 

If the cross section of a river or stream changes significantly along the distance, the 
above approach can be used with some adjustment for each cross-section change as 
follows: Assume there is a longitudinal section of a river as shown in figure 6, the 
section consists of four reaches and each reach has a different width and small changes 



14 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 
in water depth. Each reach has two cross sections 1 and 2 that represent the beginning 
and end of each reach. 

The goal is to calculate the contaminant concentration at section 2 of reach 4, i.e. C2-4. 
Continuity is valid which means that the amount of flow through each reach is the same, 
i.e. no losses in the total volume of water passing. To calculate the contaminant 
concentration C2-4, follow the steps below. 

1- Calculate V1-1, Am, C1-1, M is known; 

2- Calculate C1-2 ; 

3- Use C1-2 = Cz-i, then calculate M2-2 and C2-2; 

4- Use C2-2 = C3-1; then calculate C3-2 and etc. 



Fig. 6: Illustration of 
varied longitudinal 
section of river. 





11 2| 






1 2 


h 2! 




11 2 






















i I 


. 


1 ' 




J R1 


R2 


R3 


R4 V 



River or stream calculations can be done either manually by assuming one or two 
reaches for the entire stream length or by using a spreadsheet calculation (as shown 
below) or any other tool that users find appropriate. 



15 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

4- Examples 

This section provides two examples that illustrate the method and analytical solution 
shown above. 

Example 1: 

Let us assume a wastewater treatment plant discharges its effluent into a small stream 
with a water depth of 0.8m and a width of 6.0m and a flow velocity of 0.2m/s, figure 7. 
The wastewater treatment plant discharges 0.04m 3 /s of chemical A with a concentration 
of 18mg/l into the stream. The concentration of chemical A in the stream upstream of the 
wastewater treatment plant is 0.22mg/l. Assume no dispersion and full instantaneous 
mixing with a dilution coefficient of 1.2d _1 . What is the concentration of chemical A 3km 
downstream of the wastewater treatment plant? At what distance downstream from the 
wastewater treatment plant will the concentration of chemical A in the stream be 
0.22mg/l? 



Discharge 



ll 



Wastewater treatment discharge 

Fig. 7: Illustration of example 1. 

Solution: 

Q stream = 0.8*6.0*0.2 = 0.96m 3 /s 

Velocity after the WWT= (0.96+0.04)/(0.8*6) = 0.21m/s 

C downstream of the WWT, Eq. 3 = (0.96*0.22 + 0.04*18)/ (0.96+0.04) = 0.9312mg/l 

C at 3000 m, Eq.5 = 0.9312 ^H 1 - 2 * 3000 ^ 600 * 24 * - 21 )] = 0.7636mg/l 

X at C=0.22 mg/1, Eq.5 => 0.22=0.9312* eH 1 - 2 *^ 3600 * 24 )] -» t = 149874.3s, V=0.21m/s 

Then X= 21,706m from the discharge position. 



16 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

Example 2: 

Let us assume an intake as shown in figure 8. In this figure, the distance of the 
boundaries of IPZ-1, 2, and 3 from the intake is Di, D2, and D3, respectively and the flow 
direction is from left to right. 

Flow Direction 




<0)SW-Intake 



IPZ-3 Boundary IPZ-2 Boundary IPZ-1 Boundary 

Fig. 8: Illustration of intake protection zone distances, example 2. 

Assume a spill of a specific contaminant of 10,000kg occurred at a point upstream from 
the intake. The river has a width w = 75m and an average water depth d = 1.5m, a 
discharge of Q = 90m 3 /s and an energy slope of 0.0004. Assume the first order decay rate 
of this contaminant is 5.E-5s _1 . Calculate the concentration of the contaminant at a 
distance 40km from the spill location with decay and without decay. 

Solution: 

A spreadsheet is used to calculate the maximum concentration at a distance of 40km 
from the intake. Figure 9 shows the distance X that represents D3 for the delineation of 
IPZ-3. Based on the type of contaminant of concern, the parameters shown in figure 9 
may change. The spreadsheet can now be used to calculate the maximum concentration 
that reaches the intake. The user will need to determine the concentration at the intake 
that could be used as a threshold to decide whether the contaminant has reached the 
intake or not. 



17 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

OVEN 

Mass M(kg) 
River width w (m) 
River depth d (m) 
Discharge Q(m /s) 
Energy Slope S(-) 
Decay coefficient 1 (s" ) 

REQUIRED 

Distance X(m) 

CALCULATED 

Hydraulic Piermeter P (m) 

Hydraulic Radius (m) 

Shear velocity u* (m/ s) 

Velocity V(m/s) 

Long. Dispersion K^fm /s) 

Max. Con. w/ o decay (kg/ m ) 

Max. Con. with decay (kg/ m ) 



10000 




















75 




















1.5 




















90 




















0.0004 




















5.00E-05 




















XI 


X2 


X3 


X4 


X5 


X6 


X7 


X8 


X9 


X10 


100 


1000 


5000 


10000 


15000 


20000 


25000 


30000 


35000 


40000 


78 




















1.44230769 




















0.07523042 




















0.8 




















169.268434 




















0.17242874 


0.0545268 


0.024385107 


0.01724 


0.01408 


0.01219 


0.01091 


0.00996 


0.00922 


0.00862 


0.17135442 


0.0512231 


0.017840525 


0.00923 


0.00551 


0.00349 


0.00229 


0.00153 


0.00103 


0.00071 





0.2 - 
0.15 

0.1 
0.05 - 
- 




Transport function 


— 0— with first order decay function 




— *-»— wimoui aecay iuncuon 


= 

e 

S 




s 
= 

3 




•"*• * — rr*? 1 o — 


o 








? 


T > 5 1 



5000 10000 15000 20000 25000 

Distance (m) 



30000 



35000 



40000 



45000 



Fig. 9: Illustration to calculate the maximum concentration as a function of distance. 



18 



Technical Bulletin: Delineation of Intake Protection Zone 3 
Using the Event Based Approach (EBA) 

5- References 

1- Chin, D.A. (2006). "Water-Quality Engineering in Natural Systems", John Willey & 
Sons, INC., Publication, New Jersey, USA. 

2- Genereux, D.P. (1991). "Fields Studies of Stream flow Generation using Natural and 
Injected Tracers on Bicford and Walker Branch Watersheds" , Ph.D Dissertation, 
Massachusetts Institute of Technology, Boston, USA. 

3- Hemond, E. Fechner-Levy (1999). "Chemical Fate and Transport in the 
Environment", Academic Press, Cambridge, USA. 

4- Howard, P.H., R.S. Boethling, W.F. Jarvis, W.M. Meylan, and E.M. Michalenko 
(1991). "Handbook of Environment Degradation Rates", Lewis Publishers, Chelsea, 
Michigan, USA. 

5- McCuen, R.H. (1998). "Hydrologic Analysis and Design". Second edition, Pearson 
Education, Prentice Hall, University of Marylandy, USA. 

6- USDA National Resources Conservation Service (1986). "Urban Hydrology for Small 
Watersheds" , Technical Release 55. 

7- Wanner, O., T. Egli, T. Fleischmann, K. Lanz, P. Reichert and R.P. Schwarzenbach 
(1989). "Behaviour of insecticides Disulfoton and Thiometon in the Rhine River: a 
chemodynamic study", Journal of Environmental Science and Technology, Vol.23, No. 
10: PP 1232-1242. 



19